Mysar is a project that loads the squid logs into a mySQL database, and then runs a nice PHP interface. We just started using it a work and I have to admit I'm impressed. It is not very very difficult to install but it does require some cron jobs.

I'm not sure if the project is under active development or not, but it does a good job of loading the logs into mysql where they are easy to play with. We are looking into extending it to fit our situation a little better.

I use Free-SA which is similar to SARG but much faster and doesn't crash on huge log files. It works very well.

"Free-SA is statistic analyzer for daemons log files similar to SARG. Its main advantages over SARG are much better speed (7x-20x times), more reports support, crossplatform work and W3C compliance of generated HTML/CSS reports code."